• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.2
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• pp.104-112
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• 2007

We developed a $7{\times}7$ parallel multiplier using LTPS-TFT. The proposed multiplier has multi-valued logic 7-3 Compressor with folding, 3-2 Compressor, and final carry propagation adder. Architecture minimized the carry propagation. And power consumption reduced by switching the current source to the circuit which is operated in current mode. The proposed multiplier improved PDP by 23%, EDP by 59%, and propagation delay time by 47% compared with Wallace Tree multiplier.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.5
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• pp.1099-1103
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• 2016

The user's secret key can be retrieved by the leakage informations of power consumption occurred during the execution of scalar multiplication for elliptic curve cryptographic algorithm which can be embedded on a security device. Recently, a carry random recoding method is proposed to prevent simple power and differential power analysis attack by recoding the secret key. In this paper, we show that this recoding method is still vulnerable to the differential power analysis attack due to the limitation of the size of carry bits, which is a different from the original claim.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.913-916
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• 2009

This paper describes a hardware design of hash processor which implements HAS-160 algorithm adopted as a Korean standard. To achieve a high-speed operation with small-area, the arithmetic operation is implemented using a hybrid structure of 5:3 and 3:2 carry-save adders and a carry-select adder. The HAS-160 processor synthesized with $0.35-{\mu}m$ CMOS cell library has 17,600 gates. It computes a 160-bit hash code from a message block of 512 bits in 82 clock cycles, and has 312 Mbps throughput at 50 MHz@3.3-V clock frequency.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1748-1751
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• 2002

An expression for the average carry propagation delay in a ripple carry adder is obtained which is exact up to terms of the order 0(n$\^$-1/ln n). The case of several adders working in parallel is also considered.

• Journal of the Korean Chemical Society
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• v.53 no.6
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• pp.765-773
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• 2009

The purpose of this study is to identify secondary chemistry teachers' abilities to carry-out experiment lesson successfully. As far as the research method is concerned, literature reviews, analyses of abilities to carry-out experimentation from science textbooks, and a survey of science teachers' perceptions of experimental ability were employed along with the progressive discussions among the authors. In order to identify secondary chemistry teachers' abilities to carry-out experimentation, we divided the experiment lesson into three stages of preparation, conduct and arrangement, and management of lab, and added the stage of safety. Each stage is classified into sub-areas, and the sub-area consists of subordinate elements. The safety stage was included separately to emphasize the importance of the safety issue in lab and experimental activities. The secondary chemistry teachers' abilities to carry-out experimentation are the abilities to perform experiments in person, presupposing the instruction of experiment, and can be featured with the use of reagent and measuring instruments, the preparation of sample, designing experiment, correct experimental habit and skillfulness, data processing, analysis and reasoning, and management of lab and safety.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.6
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• pp.502-510
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• 2009

Multiprecision squaring is one of the most significant algorithms in the core public key cryptography operation. The aim of this work is to present a new improved squaring algorithm compared with the MIRACL's multi precision squaring algorithm in which the previous work [1] on multiprecision multiplication is implemented. First, previous works on multiprecision multiplication and standard squaring are analyzed. Then, our new Lazy Doubling squaring algorithm is introduced. In MIRACLE library [3], Scott's Carry-Catcher Hybrid multiplication technique [1] is applied to implementation of multiprecision multiplication and squaring. Experimental results of the Carry-Catcher hybrid squaring algorithm and the proposed Lazy Doubling squaring algorithm both of which are tested on Atmega128 CPU show that proposed idea has achieved significant performance improvements. The proposed Lazy Doubling Squaring algorithm reduces addition instructions by the fact $a_0\;{\ast}\;2\;+\;a_1\;{\ast}\;2\;+\;...\;+\;a_{n-1}\;{\ast}\;2\;+\;a_n\;{\ast}\;2\;=\;(a_0\;+\;a_1\;+\;...\;+\;a_{n-1}\;+\;a_n)\;{\ast}\;2$ while the standard squaring algorithm reduces multiplication instructions by the fact $S_{ij}\;=\;x_i\;{\ast}\;x_j\;=\;S_{ij}$. Experimental results show that the proposed squaring method is 25% faster than that in MIRACL.

• Survey Research
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• v.11 no.1
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• pp.1-18
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• 2010

We compare various imputation methods for compensating wave nonresponse that are commonly adopted in many panel surveys. Unlike the cross-sectional survey, the panel survey is involved a time-effect in nonresponse in a sense that nonresponse may happen for some but not all waves. Thus, responses in neighboring waves can be used as powerful predictors for imputing wave nonresponse such as in longitudinal regression imputation, carry-over imputation, nearest neighborhood regression imputation and row-column imputation method. For comparison, we carry out a simulation study on a few income data from the Korean Welfare Panel Study based on two performance criteria: predictive accuracy and estimation accuracy. Our simulation shows that the ratio and row-column imputation methods are much more effective in terms of both criteria. Regression, longitudinal regression and carry-over imputation methods performed better in predictive accuracy, but less in estimation accuracy. On the other hand, nearest neighborhood, nearest neighbor regression and hot-deck imputation show higher performance in estimation accuracy but lower predictive accuracy. Finally, the mean imputation shows much lower performance in both criteria.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.907-909
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• 2016

In this peper, we proposed efficient network structure using UAV squad in DTN. In Delay Tolerant Network(DTN), the routing protocols adopting store-carry-forward method are used for solving network problem occurred by the unstable network environments. This routing method is useful for work in disaster and battle field so many researches are in progress. This paper is part of that, we use UAV squad in DTN which is dynamic environments for efficient network structure. Propsed measure use environment information in disparate sensor node and organize UAV squad for stable network.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.7
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• pp.53-61
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• 2004

In this paper, we proposed a new architecture of MAC(Multiplier-Accumulator) to operate high-speed multiplication-accumulation. We used the MBA(Modified radix-4 Booth Algorithm) which is based on the 1's complement number system, and CSA(Carry Save Adder) for addition of the partial products. During the addition of the partial product, the signed numbers with the 1's complement type after Booth encoding are converted in the 2's complement signed number in the CSA tree. Since 2-bit CLA(Carry Look-ahead Adder) was used in adding the lower bits of the partial product, the input bit width of the final adder and whole delay of the critical path were reduced. The proposed MAC was applied into the DWT(Discrete Wavelet Transform) filtering operation for JPEG2000, and it showed the possibility for the practical application. Finally we identified the improved performance according to the comparison with the previous architecture in the aspect of hardware resource and delay.

• Journal of The Korean Association For Science Education
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• v.28 no.8
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• pp.870-879
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• 2008

The purpose of this study is to investigate laboratory abilities to carry-out experimentations in the field of 'Matter' in middle school science texts. A total of 359 chemistry experiments from 26 textbooks has been analyzed. The authors of this study are interested in what science process skills are required for students to perform the experiments and how often these skills are needed. This article introduced a framework for analyzing the science process skills and their frequency. There are similar patterns of science process skill use among the different grades of middle school texts. The process skills of organizing results, interpreting data and making generalizations are most needed by the order of frequency. However, abilities related to alternative activities and/or conditions show relatively low frequency. For seniors, various laboratory abilities to carry out experiments are needed, whereas abilities for operating and setting up an experimental apparatus are required in freshmen and juniors. These results suggest avenues for science teachers that make lesson plans involving science experiments.